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1、Polymer SolutionWhat is polymer solution?Why to study polymer solution?HOW to study polymer solution?3 QuestionsWhat is polymer solution?TraditionalCoverWhy to study polymer solution?Study Best method on investigation of a single polymerApplictionsBondDopeFilaturePlastic enhancedBlendHOW to study po
2、lymer solution?Polymer solution processPolymer solution processHow to select a solventHow to select a solventSolution stateSolution state：Interaction Interaction solution and separate solution and separateSolution thermodynamicsSolution thermodynamicsJosiah Willard Gibbs (1839-1903)Gibbs 方程 G=H-TSIn
3、sluable，Phase Seperate 状态Key points for polymer dissolvingLinear polymersSwelling to solutionCross-linked polymersOnly swellingCrystalline polymersMelting to solutionSolvent selectionSimilar dissolve mutually theory PolarityPolarityNon- PolarityNon- Polarity(2) Similar solubility parameterGibbs free
4、 energy 自由能Enthalpy 焓Entropy 熵Condition of solutionDuring solution processSolubility parameter = 1/2 =CED Cohesive energy densityTherefore HM is the key (a)Polar polymer to polar solvent， HM 0, Solution is depended on the comparison of HM and T SM. HM T SM, Soluble 。 HM need be more little 。Hildebra
5、nd equation 1, 2 Volume fraction of Solvent and polymer, respectively . 1, 2 Solubility parameter fraction of Solvent and polymer, respectively .VM Volume after blending Hildebrand J., Scott R.L., Solubility of Nonelectrolytes, Reinhold Publishing Corporation, New York, Chapter 7 (1949)In general,Po
6、lymer is insolubleHildebrand function is good for non- or weak polar polymerFor polar polymer, Hansen公式公式:Blend solvent：How to get ? = 1/2 =( (a) Swelling methoda) Swelling method：Cross-linked polymer is dissolved in different solvents. The Cross-linked polymer is dissolved in different solvents. Th
7、e of the solvent with the largest swelling volume is the of the solvent with the largest swelling volume is the of of polymer.polymer.(b) Viscoelasticity methodPolymer is dissolved in different solvents. The of the solvent with the largest solution viscoelasticity is the of polymer.聚合物各结构基团的摩尔引力常数聚合
8、物各结构基团的摩尔引力常数重复单元的摩尔体积重复单元的摩尔体积(c) CalculationPMMA269303.465.6668.2303.4F=269+65.6+668.2+303.4*2=1609.6V=M/=(5C+2O+8H)/1.19=100/1.19 statusGood solventBad solvent“Polymer-Solvent interaction factor 1 Si3.2.2 Thermodynamics of polymer solutions Flory-Hunggins Theory (Mean-field theory)Analogous to re
9、gular solution in alloysA-B alloysPolymer solutionThree Hypotheses 三点假设三点假设1.Polymer in solution is arranged like crystal.2.Polymer is flexible。3.Chains of polymer is dissolved uniformly 。Dissolving processPolymer entityPolymer disorientationSolventPolymer SolutionSdisorientationSsolventSdisorientat
10、ion（5） - state（ 状态）Similar to ideal solution Condition - 状态（6）Discussion of Hunggins parameterChemical potentialMore stableGood solvent良溶剂良溶剂Chemical potentialNot stableBad solvent劣溶剂劣溶剂Phase equilibrium of polymer solutionOsmotic pressure SolutionSolventSemipermeable membrane 半透膜：允许小分子通过，不允许大分子通过。W
11、hat is the physical meaning of the second Virial coefficient A2?Molar volume of solventDensity of soluteWhat we can get from the following equation?(2) A2 Second Virial coefficientIntercept=Slope coefficient=Interceptslope(1) Number average molecular weight MnDiscussion of A2 status良溶剂良溶剂劣溶剂劣溶剂A2=0A
12、20A20Huggins parameterStatusSecond Virial coefficientDiscussion of the plot(a) Add bad solvent into good solvent(b) Decrease temperature solvent temperatureStable, metastable and non-stable regions GM can be substituted by 1 and TemperatureCritical pointDifferent phase equilibrium diagramsPhase sepa
13、ration and dissolution are controlled by three variables: temperature, pressure, and concentration.LCST- Low critical solvency temperatureUCST- Ultra critical solvency temperatureTypical polymer-solution phase equilibrium diagramWeak concentrationHigh concentrationCharacteristic-Non-symmetrye.g. PVC raincoat, using plasticizer
